Dry kiln



L F.' HIRT.

DRV KILN.

APPLlATloN FILED ocT. 29, 1921.

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Patented Oct. il?, 11922.

DRY KILN.

I. F. HIRT.

'APPLICATION FILED OCT. 29, 1921.

Patented @et il?, ,19.22

nutren stares JOSEPH FRANK BERT, OF CH'ICAG'O, ILINOXS.

DRY KILIM'.

Application filed October 29, 1921. Serial No. 511,382.

To all whom t may concern:

-Be it known that JosEPn FRANK Hin'r, citizen of the United States, residing at Chil cago, in the county ot- Cook and State ol illinois, has invented certain new and useful Improvements in Dry Kilns, of which the following is a specication, reference being had therein to the accompanying drawings.

The invent-ion relates to drying rooms for lumber, veneers, glue joints in panel cores, completed panels and other articles made of wood, as well as coatings of varnish, stains, fillers, enamels and paints on articles of furniture, vehicles, interior decorations, etc.; also brick, tile, terra cotta and other articles of earthenware, aswell as macaroni, noodles, fruits, vegetables and all other articles of food that require .a scientific process in reducinr the inherent natural moisture content. r`However, the invention is particularly adapted for use in connection with drying rooms commonly known as dry kilns for lumber and veneers.

Apparatus of this character has heretofore rbeen constructed with apparent lack of regard of certain essential physical laws of thermal air circulation and relative humidity, and also in such manner as would expose the product to be dried directly to the heating` units locatedeither horizontally underneath or vertically along the sides or center of the kiln. This invariably has defeated the object to be obtained, i. e., uniform temperature and humidity throughout all sections of the drying chamber. The circulation in such types ot kilns as expose the product directly to the heating units located horizontally underneath is not in the direction upwardly through the product as l has been erroneously sul posed but instead,

the air rises rapidly on all sides of the product to the top of the chamber, passing entirely around the product as the warmest air comes into contact with the product on the top it is cooled by the inherent moisture in the product. and naturally drops down y through the product pile because it can not fall against the rapidly rising air on the sides and ends of the 'pile and thus a pocket of colder and more humid air is in evidence in the center of the piled product. This necessarily being an uneven drying, it is obvious that. considerable waste of material is occasioned. therefore it is the principal objet-t of the invention to provide a kiln wherein the material therein will be uniformly dried, and at the same time dried in the shortest time possible consistent with ,l the. determinable rate of moisture trans-"2.y fusion from the innermost fibres to the surl faces of the stock Without injury. A further object is to provide a kiln having a separate heating chamber therein, and to provide means whereby the drying elements will be mixed in said heating chamber before they are admitted to the drying chamber.

A further object is to provide communieating passages from the heating chamber to the drying chamber and likewise return passages from the drying chamber to the sliding curtains on either end and between Y cars loaded with the product. These cur tains will prevent the recirculating air from passing around the product and instead will force the air to pass between the tiers or layers.

A further object is to provide means for condensing the excess humidity, at the same time accelerating the circulation.

A further object is to provide battles substantially i centrally located to spread the heated air in the lower portions of the heat'- ing chamber so that it will enter the bottom tiers of the product with the same uniformity as exists in the upper portions of the heating chamber.

With the above and other objects in view the invention resides in the combination and arrangement of parts as hereinafter set forth, shown in the drawings, described and claimed, it being understood that changes in the precise embodiment of the invention ma be made within the scope of what is claimed without departing lfrom the spirit of the invention,

In the drawings Figure 1 is a vertical transverse sectional view through the kiln showing lumber piled on cars therein.

Figure 2 is a vertical longitudinal sectional view through the kiln taken on line 2 2 of Figure 1.

Figure 3 is a horizontal sectional view taken on line 3 3 of Figure l.

Figure 4 is a horizontal sectional view taken on line P-4 of Figure 1.

Referring to the drawings. the numeral 1 designates a kiln and 2 a drying chamber therein. Located beneath the drying chamber 2 are spa-ced heating chambers 3, in which spaced heating chambers heating units l are dis iosed. Said heating units may he separately controlled from the outside of the kiln by means of valves 4 carried by pipes al) connected to main supply pipes 1C, thereby allowing the ten'iperature in the various sections 2 of the drying chamber 2 to be uniformly controlled. Underneath the product 2"7 which for purposes of illustration is shown as stacked spaced lumber is the floor of the drying chamber 2, said flooring being designated by the numerall 5. The spaces 6 located above the spaced chamber 3 and formed by the flooring 5 at each side of the chamber 2 and by the upwardly and inwardly inclined members 6a which form the tops of the chambers 3 extend towards each other and are in communication with a centrally disposed passage 7 in communication with the lower-end of theJ drying chamber 2 substantially centrally thereof. The spaces 6 form means whereby heated vapor given off from the tops 6a will be conveyed to the passage 7 where it will be mixed with the recirculating heated air, thereby utilizing all of the heat. The heating chambers 3 are formed on each side of a longitudinally and centrally disposed wall 3a, the upper end of which terminates adjacent the passage 7. which communicates with the drying chamber 2. It will be seen that the tops 6a have their inner adjacent ends spaced fromthe upper end of the wall 3a, thereby forming passages of communication 7a, which communicate with the passage T, and through which passages 7 and 7 the air during its recirculation passes in its upward movement.

Fresh air is admitted to the heating chambers 3 through longitudinally disposed air ducts 9 located on each side of the wall 3 and below the heating elements 4. Ducts 9 at spaced'intervals throughout the length of the kiln are provided with openings 9il which are controlled by dampers 9", controllable by means of rods 9C from outside of the kiln, thereby allowing an accurate and separate control of the admission of fresh air to the various sections of the kiln.

As the fresh air enters the heating chambers 3 through the ducts 9 and openings 9, it passes upwardly through the heating units 4, heating chambers 3 and thence upwardly through the passages 7, passage 7 and by the steam spray 10, which is arranged in separately controlled sections controllable by means of valves 10 located outside of the kiln, which valves are carried by supply pipes 10b leading to any source of steam supply. Therefore it will be seen that means is provided for controlling the humidity in the kiln sections 2 independently of each other. As the heated air rises into the drying chamber 2 it passes the steam spray 10 and thereby has added to it, and mixed with it the desired per cent of moisture. Located centrally in the drying chamber 2 and preferably spaced from each other and longitudinally disposed are defiectors 12, which are supported on brackets 13. It will be seen that the deflectors 12 are curved so that the air as it passes upwardly will be deflected. The product 2b is piled on kiln cars 15, and is arranged in the usual manner with sticks 2c holding the tiers or layers apart. It will be seen that the function of the curved deflectors 12 is to direct the circulation in the lower portion of the drying chamber 2 outwardly from its center and into the roduct piles 2b. Extending downwardly rom the upper side of the drying chamber 2 and adjacent the sides thereof are substantially longitudinally disposed curtains 16 which engage the tops of the product piles 2b and prevent the circulating air from passing around said product piles and force the circulating air to pass through the pile and over the surfaces of the product. As the heated and properly conditioned air enters the return passages 17 adjacent the sides of the drying chamber 2, it is drawn downwardly into the condensing passages 18, where it passes the cold water condensing coils 19, thus reducing the tem` perature ofthe air considerably and thereby increasing the rate of circulation. The condensing coils 19 also provide means for reducing the relative humidity of the recirculating air instead of exhausting greater portions of the air, to the atmosphere, which latter means are more commonly used. The condensing coils 19 through which cold water is preferably passed may be controlled by means of valves 19a carried by supply pipes 19h, which pipes and valves are disposed outside of the kiln. It will be seen that said condensing coils may be separately controlled for each section of the'kiln. EX- haust openings 20 are provided in the outer walls of the condensing chambers 18 and provide means through which a portion of the recirculating air may be exhausted to the atmosphere through the stacks 21, which preferably discharge the air as at 22 at points above the kiln proper. lt is to be understood that the spacing and number of exhaust ducts 21 may be varied to suit different requirements. The exact amount of air to be exhausted during the recirculation may be controlled by separate slidable dampers 20, which are controlled by rods 201 leading outside of the kiln` thereby providing means for controlling the exhaust of each of the stacks 21 from without the kiln. rlhe drying chamber 2 is formed into kiln sections 2a in the general arrangement of the heating, condensing and exhausting means, each section to receive a car of lumber to be dried. Longitudinally disposed curtains 23 are disposed between the ends of the kiln sections 2a, which curtains are carried by rings 24 slidably mounted on longitudinally disposed bars 25 adjacent the upper end of the drying chamber 2. lt will be seen that the curtains 23 may be easily and quickly ex-A tended longitudinally after the cars of lumber are positioned in the drying chamber 2 and can be readily brought in contact with the product from either end door of the kiln, or a back wall, or with the product on both ends of the car as ina case Where space is necessarily left between the cars, which is usual on account of non-uniform length of product.

From the above it will be seen that a kiln is provided wherein the air is circulated through thermal energy created in the heating units that said circulation can be properly con itioned with fresh air from the exterior, that said circulation can be properly lconditioned with humidity, and that the elements of fresh air and humidity can be added to and properly mixed with the recirculating air before it comes in contact with the product. Also by providing a kiln having heating units each one of which may be separately controlled from without, a kiln having fresh air intake ducts each one of which ma be separately controlled from Without, a kiln having humidiers, each one of which ma be separately controlled from without, an a kiln having exhaust stacks each one of which may be separately controlled from without. It will be seen that the atmospheric conditions in either end or side of the kiln may be controlled to overcome any and all adverse conditions of weather such as the exposure of a door end of the kiln or wall exposures through which there are usually and unavoidably a certain degree of heat losses. lt will also be seen that the adjustable sliding curtains'on either end and between the cars of the product as well as those suspended from the ceilin of the drying chamber force the circu ating air to pass through the product instead of around it.

rl`he invention having been set forth what is claimed as new and useful is 1. A drying kiln having therein a separate drying chamber through which air recirculates, a. separate heating chamber, means located in the heating chamber whereby fresh air may be admitted in separately controllable amounts to the various sections of the kiln and at points where said fresh air will be thoroughly mixed with the recirculating air before it passes into the drying chamber; means for supplying humidity to the circulating air in separately controllable amounts in the various sections of the kiln before said air comes in contact with` controlled from the exterior, and separate exhaust stacks, each of which may be controlled from the exterior, means whereby the heat given off from the top of the drying chamber is passed to and into the mainv path of circulation, thence over the surfaces of the product and thence vdownwardly to the condensing chamber and thence into the heating chamber.

3. A kiln having therein a separate drying chamber, a separate heating chamber, heating units each of which may be separately controlled from without, fresh air intake ducts each of which may be separately controlled from without, humidiers each of which may be separately controlled from without, stacks each of which may be separatel controlled from without, means where y the heat given off from the top of the heating chamber is passed into the main path of circulation, means whereby the circulation as it leaves the heating chamber and enters the drying chamber is directed to either side and into the piled product.

4. A kiln comprising a separate drying chamber, heating chamber, heating units separately controlled from the exterior, fresh air ducts separately controlled from the exterior, humiditiers separately controlled fromthe exterior, exhaust stacks separately controlled from the exterior, means for conducting the radiation from the top of the heating chamber into the main upward pat-h of circulation, and means whereby the circulation as it enters the drying chamber substantially centrally from the heating chamber is directed into the piled product, downwardly extending curtains running substantially longitudinally throughoutthe length of the kiln, said curtains being fastened to the ceiling of the heating chamber and being of sufficient length to compensate for the varying heights of the piled product so that they will actually be in contact with the product thus preventing thecirculating air from passing over the top of the piled product, slidable adjustable curtains extending vertically from the ceiling to the bottom of the drying chamberand longitudinallyfrom the ends of the drying chamber to the product and between cars of the product, said curtains mounted at the top adjacent to the short downwardly extending curtains with metal rings attached thereto on bars of the proper length to permit the curtains to be readily drawn into contact with the product between piled, between doors and the product and between kiln ends and the product. 5. A kiln of the type described having therein a separate heating chamber, the top thereof slopinv upwardly from one side to the other, said Iieating chamber being located underneath a separate drying chamber. v

6. A kiln of the character described having therein a separate drying chamber located above the separate heating chamber,

.means in said heating chamber' whereby the circulation is directed into the product by a streamlined deflector located substantially centrally near the bottom of the drying chamber, curtains whereby the circulation is forced to pass through the product, said curtains being suspended from the ceiling of the drying cham-'ber over each car of the piled product, said curtains being of suflicient length to actually contact with the product, and slidable curtains Suspended from the ceiling of the drying chamber extending to the fioor of the drying chamber and mounted at the top with rings placed therein on bars fastened to the ceiling of the drying chamber` said curtains bein of suiiicient width to permit them to be readily brought into actual contact with the product between cars, be-

tween carsand doors and between cars and ends of the drying chamber.

7. In a kiln of the type described, means whereby the circulation is directed upwardl througiglgigf a substantially centrally locate\ passage from a separate heating chamber located underneath a separate drying chamber, to a separate drying chamber located above a separate heating chamber, means for directing said circulation into the product, means whereby the circulation is prevented from passing around the product, means whereby the circulation is directed in such a manner as will cause it to passrin uniform proportions over either side of the kiln, and means 'whereby said -circulation is returned through downwardly extending passages located on either side of the drying chamber to a separate condensing chamber.

8. In a kiln of the character described, having a separate condensing chamber 1ocated adjacent the heating chamber providing means for condensing any desired amount of excess humidity from the recirculating air and means for reducing the tem` perature ofthe recirculating air before it is returned to the separate heating chamber thus increasing the rate of circulation, means located in said condensing cham-ber whereby any desired amount of the recirculating air may be exhausted to the outside atmosphere.

9. A kiln having a drying chamber, a separate heating chamber located below the drying chamber, a condensing chamber, said condensing chamber being in communication with the drying chamber andthe heating chamber, and a passage of communication between the heating cham-ber and the drying chamber.

10. A kiln having a drying chamber, spaced heating chambers disposed beneath the drying chamber and separated therefrom, passages of communication between the adjacent sides of the heating chambers with the drying chamber and passages of communication between the outer sides of the heating chambers and the drying chamber.

11. A kiln having a drying chamber, spaced heating chambers disposed beneath the drying chamber and separated therefrom, passages of communication between the drying chamber, condensing chambers,

. said condensing chambers being in communication with the heating chambers and with the drying chamber.

In testimony whereof I hereunto aix my signature.

JOSEPH FRANK HIRT. 

